The SOS Structure uses population counts from the latest Census of Population and Housing to class CDs as urban or rural. Unlike the UC/L Structure (Chapter 6), the SOS Structure includes all CDs and therefore, in aggregate, the SOS Structure covers all of Australia (as defined in Chapter 1). For the 2001 edition, three of the five different SOS were divided into sub categories based on population size.

The SOS Structure is used for the production of standard statistical outputs from Population Censuses such as Selected Social and Housing Characteristics for Urban Centres and Localities (cat. nos 2016.0-7) and CDATA2001 (cat. nos 2019.0.30.001-2019.8.30.001). It is also used to classify data collected from the labour force surveys.

The SOS Structure is maintained as a separate structure in the ASGC because SOS spatial units do not align with spatial units from any of the other structures.

THE STRUCTURE

The SOS Structure is defined only in census years. It contains three hierarchical levels, comprising in ascending order: CDs-SOS-S/Ts.

In this structure, CDs aggregate to SOS and SOS aggregate to S/Ts without gaps or overlaps. Consequently, the structure covers all of Australia.

Within a state or territory, each SOS represents an aggregation of non-contiguous geographical areas of a particular urban/rural type. The categories are:

Major Urban: this category provides for a further three categories of urban areas (Urban Centres from the UC/L Structure) based upon population ranges of 1,000,000 or more, 250,000 to 999,999, and 100,000 to 249,999

Other Urban: this category provides for a further five categories of urban areas (Urban Centres from the UC/L Structure) based upon population ranges of 50,000 to 99,999, 20,000 to 49,999, 10,000 to 19,999, 5,000 to 9,999, and 1,000 to 4,999

Bounded Locality: this category provides for a further two categories of rural areas (Localities from the UC/L Structure) with a population of 500 to 999 and 200 to 499

Rural Balance: the remainder of the S/T

Migratory: areas composed of off-shore, shipping and migratory CDs.

SOS code

SOS are identified by unique two-digit codes within each S/T. For unique Australia-wide identification, each two-digit SOS code has to be used in conjunction with the S/T code.